This application is the U.S. national phase of International Application No. PCT/FI2009/050495 filed 10 Jun. 2009 which designated the U.S. and claims priority to FI Patent Application No. 20080401 filed 11 Jun. 2008, the entire contents of each of which are hereby incorporated by reference.
The present invention relates to an apparatus for storing rolling material in an open storage pile and more specifically to an apparatus for stacking and reclaiming material, i.e. to a stacker/reclaimer. Most preferably the invention relates to storing of wood chips, but it is applicable for storing other granular material such as wood bark, coal, corn or fine-grained material.
Storage piles are needed for homogenizing the material and on the other hand for blending possibilities. The stacker/reclaimer for this kind of storage pile comprises e.g. a center column, a stacker conveyor and a reclaimer conveyor. The center column supports concentrically the upper stacker conveyor and the lower reclaimer conveyor. The stacker conveyor adds loose material in the pile, while the reclaimer conveyor conveys the material from the pile towards the slewing center of the stacker/reclaimer. In the slewing center the material to be discharged is transferred to an underground conveyor removing the material. Thus, the stacker/reclaimer is rotatable and creates an arched pile around itself.
In prior art stacker/reclaimers the center column is support with inclined, massive steel and concrete supports onto an equalizing hopper or onto the ground surface. Additionally, the concrete construction of the center column extends up to the slewing hinge. This kind of construction is heavy and expensive to build, as all the forces of the center column, also vertical, must be supported with inclined supports.
In known solutions, with a typical reclaiming capacity of 500-2500 i-m3/h (=loose cubic meters per hour, e.g. chips), the depth of the equalizing hopper's foundation has to be approximately 6 meters due to the construction of the stacker/reclaimer. A deep equalizing hopper often causes difficulties. In many places water is met closer to the ground surface, which makes digging the tunnel and the equalizing hopper difficult and expensive. Even if groundwater would not cause a problem, making a deep equalizing hopper and a tunnel is in every case expensive with massive earth-moving work. In addition, the support of the center column requires a large amount of steel and it is challenging in constructional view, and expensive to build.